The linear hydraulic motor of the present invention is suited particularly for use in a reciprocating floor conveyor, but it is believed to have general utility.
Reciprocating floor conveyors generally include an array of floor members or conveyor slats, divided into groups that operatively reciprocate back and forth along the conveyor. A hydraulic drive system operates to drive at least a majority of the groups of conveyor slats in unison in a desired load conveying direction. The drive system then retracts the groups of conveyor slats individually. Systems are in use in which all of the groups of conveyor slats are driven in unison, in the desired load conveying direction, and then are individually retracted sequentially. It has also been proposed to drive a majority of the conveyor slats in the desired load conveying direction while at the same time retracting the remaining conveyor slats. The present invention has application with both of these types of systems, as well as with any type of drive system used for reciprocating conveyor slats in a manner to walk a load onto or off of the conveyor.
For background purposes, reference is made to U.S. Pat. No. 4,821,868 of Foster, granted Apr. 18, 1989. This patent discloses a drive frame assembly for a reciprocating floor conveyor, which assembly uses linear hydraulic motors. Reference is also made to U.S. Pat. No. 4,712,467 of Foster, granted Dec. 15, 1987. This patent discloses a combination linear hydraulic motor and transfer valve particularly suited for use in driving reciprocating floor conveyors. Reference should also be made to a text entitled "Hydraulic System Analysis" by George R. Keller, and published by the editors of Hydraulics & Pneumatics Magazine, copyright 1978, Section 9.6, pages 130-132, "Actuator Stroke Snubbing." Section 9.6 discusses load alleviation devices for actuators. The foregoing references should be considered in order to put the present invention into proper perspective.
Further reference is made to U.S. Pat. No. 4,143,760, granted Mar. 13, 1979; U.S. Pat. No. 4,144,963, granted Mar. 20, 1979; U.S. Pat. No. 4,184,587, granted Jan. 22, 1980; all to Olof A. Hallstrom. Reference is also made to my U.S. Pat. Nos. 4,474,285; 4,492,303; 4,508,211; and 4,580,678.
Earlier forms of reciprocating floor conveyors are disclosed by U.S. Pat. No. 2,629,504, granted in February of 1953 to Peterson; by U.S. Pat. No. 2,973,856, granted in Mar. of 1961 to Brooks; by U.S. Pat. No. 3,534,875, granted in October of 1970 to Hallstrom; by U.S. Pat. No. 3,905,290, granted Sep. 16, 1975, to Robert A. Caughey; and by West German Patent Publication No. 1,296,087, published in May of 1969. These patents are only generally related to a particular application of the subject invention and require no further comment.